Dishwashing composition and method of making same

ABSTRACT

A DISHWASHING COMPOSITION IS PREPARED BY FIRST CONVERTIN AN ALKALI-METAL TRIMETAPHOSPHATE TO THE ALKALI-METAL TRIPOLYPHOSPHATE HEXAHYDRATE BY REACTION WITH SODIUM HYDROXIDE IN THE PRESENCE OF A SULFONATED ALKYL NAPTHALENE WETTING AGENT AND FORMULATING THE PRODUCT WITH VARIOUS COMPONENTS TO FORM A DISHWASHING COMPOSITION HAVING HIGHLY DESIRABLE CHARACTERISTICS.

3 812 045 DISHWASHING COMPOSITION AND METHOD F MAKING SAME US. Cl.252-99 5 Claims ABSTRACT OF THE DISCLOSURE A dishwashing composition isprepared by first converting an alkali-metal trimetaphosphate to thealkali-metal tripolyphosphate hexahydrate by reaction with sodiumhydroxide in the presence of a sulfonated alkyl naphthalene wettingagent and formulating the product with various components to form adishwashing composition having highly desirable characteristics.

This is a continuation of application Ser. No. 780,244 filed Nov. 29,1968, now abandoned.

Detergent compositions for use in automatic dishwashers must meet anumber of criteria such as protection of overglaie decoration of china,non-spotting of glassware, non-tarnishing of silverware, detergency forcleaning the items being washed, absence of foaming, non-caking ofcomposition on the shelf, non-gelling of the composition in the washingmachine, retention of available chlorine during shelf life forsubsequently sanitizing items in washer and others. All too frequentlythe solution to one problem results in the reoccurrence of one of theother difficulties.

The principal detergent used in dishwashing compounds is an alkali-metalphosphate, in which the ratio of M630 to P 0, is from 1 to 3:1, Me beingsodium or potassium. It is known that sodium tripolyphosphate,alkali-metal pyrophosphate or ortho-phosphate, and sodiumhexametaphospliate have been used. More recently it has been found thatsodium tripolyphosphate hexahydrate is useful. However, the presence ofexcess water of hydration, as frequently occurs when preparing thehexahydrate from the trimetaphosphate or tripolyphosphate seriouslyaffects other desirable characteristics of the composition, such as thechlorine stability, the anti-caking of the composition during shelf-lifeand the like.

Since suitable sodium tripolyphosphate hexahydrate is not obtainablefrom commercial sources it has become necessary to prepare thehexahydrate during the formulation of the composition in order toprepare the hexahydrate without the undesirable, excess water ofhydration.

According to the present invention a highly suitable tripolyphosphatehexahydrate is prepared, in situ, so to speak, which enables one toformulate a dishwashing composition having the highly desirablecharacteristics mentioned above.

More specifically, a silicate, such as an alkali-metal silicate, inwater, an alkali-metal sulfate and an anionic wetting agent such assulfonated alkyl naphthalene were combined and mixed until a consistentfoam was obtained. At this point an alkali metal trimetaphosphate wasadded and the temperature raised to about 140 F. A 50% sodium hydroxidesolution was then added. The temperature of the reaction mass rose toabout 220 F. with substantial flufling or frothing. During this reactionperiod a substantial amount of water vapor was evolved. After a shorttime the reaction subsided and the crumbly material which was nearly dryto the touch was further dried by heating at 140 F. to a constant3,812,045 Patented May 21, 1974 weight. The product containing thealkali-metal tripolyphosphate hexahydrate had a water content of 21.6%(Ohaus Moisture Analysis).

To this hexahydrate material was added about 11% of a bleach mixturecontaining an alkali metal dichloroisocyanurate, an alkali metal sulfateand a portion of the hexahydrate to provide about 1% available chlorinecontent in the final composition. This method of adding the chlorinecompound ensures thorough distribution in the composition.

The product prepared as mentioned above had excellent bleach stabilitysince no loss of available chlorine occurred after hours at F. in asealed jar; it did not have an offensive odor and it remainedfree-flowing and did not cake up. It afforded excellent cleaning anddetergent properties while offering complete safety against damage tooverglaze decoration of china.

In the above mentioned process it is usually desirable to use sodiumsilicate having a ratio of SiO,/Na,0 of from 1:2 to 1:31, sodiumsulfate, and sodium trimetaphosphate as the initial ingredients. Theanionic wetting agent is a sulfonated alkyl naphthalene product,preferably the product known as Petro-ll, which is the sulfonated methylnaphthalene material made and sold by Petrochemicals Company. Thealkali-metal dichloroisocyanurate is preferably the potassium salt butmay also be the sodium salt, if desired.

The use of the wetting agent during the conversion of thetrimetaphosphate to the tripolyphosphate hexahydrate appears to resultin a product which does not include excess moisture, which as notedabove, impairs stability and the non-caking characteristics desired.Possibly, the fluffing" or frothing of the reaction materials during theconversion reaction at high temperatures enables the excess free waterto be evolved from the reaction mixture so that only combined water ofhydration remains there- The invention will now be described withreference to the following example:

These materials were thoroughly mixed to produce a consistent foam.

368 grams of sodium trimetaphosphate were added to the reaction mixtureand the temperature was raised to about 140 F. in about 3 minutes.

192 grams of sodium hydroxide (50% solution) at about 140 F. were thenadded. In about 1 minute the temperature had risen to about 220 F. Therewas marked flufiing or frothing with strong evolution of water vaporduring the reaction which was completed in about 3 minutes. The reactionmass was crumbly" and nearly dry to the touch. It was then dried to aconstant weight at about 140 F. The reaction mass contained 21.6% waterby the Ohaus Moisture Analysis Test.

Next a bleach mixture containing about 20% by weight of potassiumdichloroisocyanurate, 30% sodium tripolyphosphate and 50% sodium sulfatewas prepared by mixing the dry ingredients. 8 parts by weight of thebleach mixture was added to 92 parts by weight of the previouslyprepared tripolyphosphate hexahydrate reaction mixture. This providesabout 1% available chlorine in the final composition.

Subsequent tests showed that the chlorine stability was excellent andthat the other criteria concerning spotting of glassware, tarnishing ofsilverware, protection of overglaze decoration of china, cleaning,sanitizing, caking during shelf-life, gelling during use, and foamingwere all excellent.

It will be understood, as is customary in this field that small amountsof a suitable perfume and, if desired, a compatible dyestuff may beadded for identification purposes or for improved saleability.

Although reference has been made above and in the appended claims tospecific compounds it will be understood to those familiar with this artthat equivalents are to be included by the terminology used.

It will be apparent that changes and modifications of the variousfeatures described herein may be made with out departing from the spiritand scope of the invention. It is therefore apparent that the foregoingdescription is by way of illustration of the invention rather thanlimitation thereof.

What is claimed is:

1. In a process for producing a dishwashing composition comprising thestep of reacting sodium or potassium trimetaphosphate with an aqueoussodium hydroxide solution to form the sodium or potassiumtripolyphosphate hexahydrate in a substantial dry form containingsubstantially no excess moisture, the improvement which comprisescarrying out the reaction in the presence of a sulfonated methylnaphthalene wetting agent and sodium silicate having a ratio of silicato sodium oxide of from 1:2 to 1:32, and subsequent to the reactionmixing said tripolyphosphate hexahydrate reaction mixture with potassiumor sodium dichloroisocyanurate.

2. A method as claimed in claim 1 wherein the alkalimetaltrimetaphosphate is sodium trimetaphosphate.

3. A method as claimed in claim 1 wherein the dichloroisocyanurate ispotassium dichloroisocyanurate.

4. A method as claimed in claim 1 wherein the silicate, water andwetting agent are pre-mixed to produce a foam and then adding thetrimetaphosphate and further comprising the step of heating the mixtureto about 140 F. prior to the addition of the sodium hydroxide solution.

5. A method as claimed in claim 1 including the fur ther step of dryingthe reaction product at about 140' F. to a constant weight prior to themixture with the dichloroisocyanurate.

References Cited UNITED STATES PATENTS 3,390,093 6/1968 Feierstein etal. 252-- X 3,248,330 4/1966 Feierstein et al. 252-99 3,454,499 7/ 1969Meyer et a1. 252-539 MAYER WEINBLATI, Primary Examiner US. Cl. X.R.

